Chapter 3: Healthy Human Function PDF

# Unit B: Cells and Systems ## 3.0 Healthy Human Function Depends on a Variety of Interacting and Reacting Systems - **Key Concepts** - Cells - Tissues - Organs - Structure and Function - Response to Stimuli - Systems - **Learning Outcomes** - Describe how various body...

# Unit B: Cells and Systems ## 3.0 Healthy Human Function Depends on a Variety of Interacting and Reacting Systems - **Key Concepts** - Cells - Tissues - Organs - Structure and Function - Response to Stimuli - Systems - **Learning Outcomes** - Describe how various body systems work. - Recognize the roles of organs and tissues in body systems - Describe how various cells help the body to function - Show how the body responds to changing conditions ### Figure 3.1 The body is comprised of many different systems, which interact with one another. These systems work together to maintain life. An example is the interaction between the circulatory system and the respiratory system: the circulatory system pumps blood throughout the body, and the respiratory system delivers oxygen to the blood and removes carbon dioxide. ## 3.1 Digestive System - Living organisms require energy to survive. - Energy comes from carbohydrates (sugars and starches), lipids (fats and oils), and proteins. - Food must be processed by the **digestive system** before cells can use it as fuel. - The digestive system breaks down food into usable particles for cells. ### Figure 3.2 The digestive system is a long tube that is made up of the mouth, esophagus, stomach, small intestine, and large intestine. ### Give it a TRY: A Taste of Digestion - Chew a soda cracker thoroughly for 5 minutes without swallowing. - How did the crackers taste as you first chewed them? - Describe how the taste changed as you neared the 5-minute mark of the test. - Compare your taste experience with that of your classmates. - What do you think caused any changes you experienced? - **Types of Digestion** - **Mechanical Digestion** involves physically breaking down food into small pieces. - **Chemical Digestion** involves using enzymes to break down large particles into smaller particles. ## Food's Path Through the Digestive System - The digestive system starts at the mouth and ends at the rectum. ### The Mouth and Esophagus - Digestion begins in the mouth with the mechanical breakdown of food. - Teeth chew food and mix it with saliva. - Saliva contains water to moisten food and the enzyme salivary amylase, which begins to break down starch into smaller sugar molecules. - When you swallow, the epiglottis (a flap of skin) covers the windpipe to prevent food from entering the lungs. - The food is transported down the esophagus toward the stomach through wave-like movements called peristalsis. ### Figure 3.3 Saliva from salivary glands moistens food in the mouth. ### Figure 3.4 Peristalsis in the esophagus: Muscle tissue contracts and relaxes to move food down the esophagus. ### The Stomach - The stomach churns food, mixing it with gastric juices. - Gastric juices contain mucus, hydrochloric acid, water, and digestive enzymes. - Hydrochloric acid helps to chemically digest proteins into smaller particles. - Mucus protects the stomach from being digested by its own juices. - The slightly acidic stomach releases food into the small intestine. ### Figure 3.5 The yellow dots are droplets of mucus produced by the stomach wall. ### Figure 3.6 Muscular walls of the stomach. ### The Small Intestine, Pancreas, Liver, and Gall Bladder - The small intestine is where chemical digestion continues. - The pancreas releases enzymes, which, along with enzymes produced by the wall of the small intestine, continue digesting starches and proteins into very small particles. - The liver produces bile, which is stored in the gall bladder. Bile breaks up large globules of lipids into smaller droplets. - The small intestine absorbs nutrient particles, which are then transported into the bloodstream by blood vessels. ### Figure 3.7 The lower part of the digestive system is comprised of the large intestine, small intestine, pancreas, liver, and gall bladder. ### Figure 3.8 A cross section of the small intestine showing villi. ### Figure 3.9 The inner structure of a villus. ### The Large Intestine - The large intestine absorbs water, some vitamins, and minerals. - Undigested food forms into feces, which is collected in the rectum. ## 3.2 Respiratory System - Your respiratory system is responsible for supplying your blood with oxygen and removing carbon dioxide. ### Give it a TRY: What's in Your Breath? - Add 10 mL of water and a few drops of bromothymol blue to two test tubes. - Label the first test tube "A" and the second "B." - Gently blow 5 breaths into the liquid of test tube "A" using a straw. - Bromothymol blue changes color when mixed with carbon dioxide. Did the color of test tube "A" change? How did the results of the experiment prove that your exhaled breath contains carbon dioxide? Why was it important to include test tube "B"? ### infoBIT: How's the Air Up There? - Mountain climbing is dangerous at high altitudes due to the lower levels of oxygen. - Your respiratory system tries to compensate by acclimatizing and breathing deeply. - However, the brain's function and coordination are affected by the lack of oxygen. - **Breathing** - The respiratory system uses the chest and diaphragm muscles to move air in and out of the lungs. - When you inhale, your chest and lungs expand, which pulls air into your lungs. - When you exhale, your chest and lungs contract, which forces air out. ### Figure 3.11 Movement of the ribs and diaphragm during breathing: The diaphragm moves downward during inhalation and upward during exhalation. ### Figure 3.12 The pathway of air into the lungs: Air enters the respiratory system through the nose, mouth, trachea, and bronchi, before entering the lungs. - **The Gas Exchange Process** - Cells require oxygen to release energy from nutrients. - Cells also need to release carbon dioxide waste gas from the body. - The respiratory system works with the circulatory system to allow gas exchange between the cells and the blood. ### Figure 3.13 Alveoli are hollow sacs surrounded by capillaries. Gas exchange occurs between the alveoli and capillaries. - **Alveoli** are tiny, air-filled sacs at the ends of bronchioles. - **Bronchi** are tube-like passageways connecting the trachea to the lungs. - **Bronchioles** are smaller branches of bronchi. - **Capillaries** are tiny blood vessels that surround alveoli. - Oxygen naturally diffuses from the alveoli (high oxygen concentration, low carbon dioxide concentration) into the capillaries (low oxygen concentration, high carbon dioxide concentration). - Carbon dioxide naturally diffuses from the capillaries into the alveoli. ## 3.3 Circulatory System - The circulatory system transports nutrients and waste products throughout the body. - The circulatory system transports oxygen to cells and removes carbon dioxide. ### Figure 3.14 How is your circulatory system similar to a highway interchange? The circulatory system is a network of vessels (like roads) that deliver substances (like vehicles) to different locations. ### Figure 3.15 The circulatory system is composed of blood vessels, which carry blood. Arteries carry blood away from the heart. Veins carry blood toward the heart. ### Give it a TRY: What Do You Know? - Where is the blood located? How does it move around your body? - Why is some blood bright red and some blood dark red? ### The Heart - The heart is a pump that circulates blood through two separate loops. - The right side of the heart pumps blood to the lungs to receive oxygen. - The left side of the heart pumps oxygen-rich blood to the rest of the body. ### Figure 3.16 Blood flow though the heart. Blue arrows show the path of blood low in oxygen, and red arrows show the path of blood high in oxygen. ### Figure 3.17 The heart circulates blood through two loops. The first loop pumps blood to the body. The second loop pumps blood to the lungs. ### infoBIT: They've Got the Beat - The animal with the fastest heart rate is the hummingbird. - The slowest heart rate is that of the elephant. - **Arteries, Veins, and Capillaries** - **Arteries** carry blood away from the heart. - **Veins** carry blood toward the heart. - **Capillaries** connect arteries and veins. - Arteries are thicker than veins and have a thick muscular wall. - Arteries are able to expand and contract, which helps to push blood along. - Veins are thinner than arteries and have valves to prevent blood from flowing backward. ### Figure 3.18 Tissues of an artery, capillary, and vein. ## 3.4 Excretory System - The excretory system removes waste products from the body. - Waste products can be harmful to the body if they are not removed. ### Figure 3.24 Organs of the excretory system: kidneys, ureter, bladder. ### Give it a TRY: Where Does it Go? - On any given day, you may take in about 2.5 L of water. - What happens to this water? - Match the following mechanisms for getting rid of water with the correct amount: 0.5 L, 0.8 L, 1.2 L. Sweat, urine and feces, breathed out air. - **Waste Products** - Carbon dioxide is removed from the blood by the lungs during the gas exchange process. - Ammonia is produced during the breakdown of proteins. - Ammonia is converted to urea by the liver. - Urea is removed from the blood by the kidneys as part of urine. - Water and salts are also removed from the body as waste products. ### The Liver - The liver is part of the digestive system that also has an important role in excretion. - The liver converts harmful ammonia into urea. ### The Kidneys - The kidneys filter blood to remove waste products, including urea, water, and salts. - The kidneys produce urine: about 1.5 L of urine per day. ### Figure 3.25 The structures of the excretory system. Blood enters the kidney through a renal artery, and leaves the kidney through a renal vein. ### The Formation of Urine - Filters in the kidney called nephrons remove wastes from the blood and produce urine. - Renal arteries carry blood to the kidneys. - Clean filtered blood returns to the body through the renal vein. - Urine flows out of the kidneys through the ureters. ### Ureters, Bladder, and Urethra - The ureters are tubes that connect the kidneys to the bladder. - The bladder is a sac that holds urine, until the urine is excreted through the urethra. ### The Skin - The skin excretes salts through sweat. ### Figure 3.26 This athlete is excreting salt. ### Give it a TRY: Testing Artificial Urine - Label three test tubes: water, glucose, protein. - Label three other test tubes: patient 1, patient 2, patient 3. - Fill the test tubes with the appropriate liquids: water, glucose solution, protein solution, simulated urine samples. - Use glucose test strips to test for the presence of glucose in each test tube. - Use Biuret solution to test for the presence of protein in each test tube. ### Check and Reflect - What is the function of the excretory system? - What is urea and how is it formed? - If your water intake on a certain day were higher than usual, how would your body respond to this? - A freshwater fish produces a lot of urine, and a camel produces very little urine. Explain why this is so. ## 3.5 Nervous System - The nervous system monitors and responds to stimuli. - The nervous system allows the body to react to changes in the environment. - The nervous system consists of the central nervous system and the peripheral nervous system. ### Figure 3.29 A goalie reacting to a stimulus: The flying puck. ### Figure 3.30 MRI scan showing the structures of the human brain. - **Neurons** - Neurons are specialized cells that comprise nervous tissue. - Neurons send and receive messages. - Neurons have three main parts: dendrites, the cell body, and the axon. - **Dendrites** receive messages from other neurons. - The **cell body** contains the nucleus of the neuron. - The **axon** transmits messages from the cell body to other neurons. ### Figure 3.31 Structure of two neurons: One neuron receives a message from another, which transmits this message to a third neuron. - **How the Nervous System is Organized** - The **central nervous system** is comprised of the brain and the spinal cord. - The **peripheral nervous system** is comprised of the cranial and spinal nerves. ### Figure 3.32 Structures of the nervous system: The central nervous system, the cranial nerves, and the peripheral nerves. ### The Peripheral Nervous System - The peripheral nervous system connects the central nervous system to the rest of the body. - **Sensory neurons** carry information from the body to the central nervous system. - **Motor neurons** carry information from the central nervous system to muscles and organs. ### The Central Nervous System - The central nervous system receives stimuli from the outside world, as well as internal stimuli. - The central nervous system controls the body's responses to stimuli. - The brain is divided into three main sections: the cerebrum, cerebellum, and medulla. ### Figure 3.33 Functions of the brain. The cerebrum controls thinking, talking, and moving. The cerebellum controls balance. The medulla controls breathing and the beating of the heart. - The spinal cord connects the brain to the peripheral nervous system. - The spinal cord serves as a highway for messages between the brain and the body. - **Interneurons** connect one neutron to another. ### The Reflex Response - A **reflex** is an automatic response by the nervous system to an external stimulus. - Reflexes do not involve the brain. - A reflex is a rapid response that can help to protect the body from harm. ### Figure 3.34 The path of a reflex: A stimulus (i.e., touching a hot object) is received by a sensory neuron, which sends a message to the spinal cord. This message is relayed through an interneuron to a motor neuron, which causes the muscles to react to the stimulus (i.e., quickly remove the hand from the hot object). ## 3.5 A Soft Touch - The skin contains receptors that sense touch, heat, cold, pain, and pressure. - The distribution of touch receptors is not even across the body. ### Give it a TRY: A Soft Touch - Use a drafting divider to test the sensitivity of the skin on different body parts. - Close your partner's eyes and gently touch their fingertip with the two ends of the drafting divider. - Slowly decrease the distance between the ends, until your partner reports only feeling one point. - Record your data in a table and rank the body parts from most sensitive to least sensitive. ### Check and Reflect - Does your data support the hypothesis? - Why do you think certain areas of the body have a keen sense of touch?